Like humans and other animals, plant life such as trees are susceptible to becoming afflicted with various diseases. Sometimes the trees may be saved with proper treatment; but it is often more effective to innoculate the trees in the first instance to provide an immunity against various diseases.
For example, a disease called "lethal yellowing" has caused the destruction of most of the coconut palms in South Florida. Lethal yellowing is a virus-like disease which is usually incurable. It is spread by a small insect called a leaf hopper which is carried by the wind. The trees afflicted with the disease of lethal yellowing exhibit the following symptoms: the fronds turn bright yellow and drop; the orange flowers turn brown; and the coconuts darken and drop. Other varieties of palm trees are also susceptible.
This disease started in the Florida Keys and rapidly spread northward. Since 1972, according to published statistics, 95% of the coconut palms in Dade County, 85% in Broward County and 75% in Palm Beach County have died from lethal yellowing. Within the latter county, the town of Palm Beach has pumped hundreds of gallons of the antibiotic tetracycline into its palm trees and has spent over a million dollars since 1972 in innoculating its trees against this dreaded disease. The residents of Palm Beach are very proud of their beautiful arching palm trees and are determined to preserve them.
In the prior art, various devices and instruments have been employed for injecting a liquid into a tree or other plant for the purpose of destroying insects which infest the tree, innoculating the tree against various diseases (such as lethal yellowing), and providing nourishment to stimulate growth. Generally, an opening is bored into the trunk of the tree, and the liquid is injected into the tree under pressure by means of a suitable coupling, such as the needle of a hypodermic syringe. Examples of this known prior art are U.S. Pat. Nos. 1,756,453; 2,116,591; 3,864,874; 4,011,685; and 4,342,176.
In the aforementioned '874 patent, a horizontal bore and a counterbore (or countersink) are drilled into the trunk of the tree, and a plastic capsule is pressed into the bore and is retained therein by a frictional fit. The capsule has a flange portion seated on a rubber gasket in the counterbore, thereby providing a seal to preclude the escape of liquid out of the capsule. A hypodermic needle is forced through the end wall of the capsule, creating a small opening therein to inject the liquid into the capsule, and the needle is subsequently withdrawn. The liquid passes through openings formed in the cylindrical wall of the capsule, intermediate its ends, and into the cambiem layer in the tree.
Generally speaking, these prior art methods are somewhat cumbersome and costly and are not totally effective in injecting a liquid into a tree for the purpose of providing nutriment to the tree, innoculating the tree against diseases such as lethal yellowing, or for other purposes.